Process flare systems are widely used in the refining, chemical, petrochemical, petroleum production, and other industries for burning flammable and/or toxic materials which are released due to upset or startup conditions, or which are released simply as a result of the process itself. Flare stacks and other flare systems typically include one or more flare pilot burners which must remain in continuous operation in order to ignite the materials which are disposed of through the flare system.
A need exists for an apparatus and method for monitoring process flares and flare pilot burners which (a) provide reliable, instantaneous feedback, (b) are capable of identifying and monitoring each individual pilot burner in the flare system, as well as the flare itself, and (c) can be repaired, maintained or replaced without taking the flare system out of operation.
In order to prevent serious injury or illness resulting from the release of toxic substances, and to protect the plant personnel and the processing facility itself from harm due to fire and/or explosion, it is imperative that the operating status of the pilot burners used in the flare system, as well as the flare itself, be known or instantaneously determinable at all times. The systems heretofore available in the art for monitoring flares and flare pilot burners have involved (a) the use of long distance optics, (b) the use of thermocouples positioned in the combustion flames, or (c) flame rod ionization. Unfortunately, these existing systems and techniques have significant shortcomings and are not entirely reliable.
The optical monitoring systems currently employed in the art require the use of long distance lenses which are mounted at grade at a safe distance from the flare. Because of the distance involved, the viewing lens can be obstructed by fog, rain, snow, dust, smoke, or other conditions. The long distance viewing systems are also difficult to aim and are subject to movement over time. Further, the long distance viewing systems must be set to view an area large enough to account for significant differences in the actual position of the flame which can be caused by changing wind conditions. Consequently, for these and other reasons, the long distance viewing systems typically cannot adequately distinguish, for example, between the flame produced by a flare pilot burner versus the flame produced by the flare itself.
Thermocouple and flame rod ionization systems, on the other hand, require that the thermocouple or ionization rod be positioned in or substantially in the flame itself, thus causing rapid degradation which severely limits the useful life of these components. The replacement of such components is costly and is typically difficult, or sometimes impossible, to accomplish without taking the flare out of operation. Moreover, thermocouple and ion rod systems are also deficient in that (a) thermocouples do not provide sufficiently rapid temperature responses for instantaneous flame recognition and (b) ionization rods are viewed to be unreliable and prone to operational problems and difficulties in open environments.